Process of producing calcium carbide and pig iron



H. ELDRIDGE 1.719.970

PROCESS OF PRODUCING CALCIUM CARBIDE AND PIG IRON I July 9, 1929.

Filed March 8, 9

INVENTOR ///LL/4/? YfL 06/065 BY 1% ATTORNEYS Patented July 9, 1929.

UNITED STATES PATENT OFFICE.

HILLIABY ELDBIDGE, OF OAKLAND, CALIFORNIA, ASSIGNOR F ONE-SIXTEENTH TO HAIRY ELLIOT MCGHEE, OF OAKLAND, CALIFORNIA, ONE-SIXTEEN'III '10 MARY ELIZABETH WALDRON, OF ALBANY, CALIFORNIA, AND BY DEGREE 0F COURT EEVEN-EIGPTTHS TO MARTHA KIESLICH ELDRIDGE, WIDOW OF SAID HILLIARY BIIDBIDGE, DECEASED.

rnoonss or rnonvcme CALCIUM cannmn AND no IRON.

Application filed larch s, 1927. Serial No. 173,763.

The present invention relates to improvements in a process for producing calcium carbide and pig iron and its particular object is to combine the two processes intoone opera- 6 tion, allowing the iron oxide to be reduced in the manufacture of calcium carbide without increasing the cost of the procedure so that the reduction of iron oxideis accomphshed without expense.

A further object of the invention is to disclose a sim lified process of producing calcium carbi e in connection with the reduction of iron oxide which allows calcium carbonate to be used as one of the ingredients of II the mixture to be treated for producing cal cium carbide, while thus far it has been considered necessary to first calcine the calcium carbonate before mixing the same with carbon for the production of calclum carbide. My process is preferably carried out m an electric furnace and in the presence of a draft exercising continuous suction on the surface of the mixture treated in the furnace for preventing an equilibrium from being established between the vapors rising from the mixture under the influence of the heat and the mixture. A furnace was adaptedfor thls purpose as has been described in detail in my co-pending application, Serial #31,391 and will be briefly referred to in the present spec1- fication as far as is necessary for carry ng out my recess.

T e said furnace was particularly designed for the production ofcalcium carbide by subjecting a mixture of lime and carbon to the heat of an electric arc and for utihzmg the carbon monoxide formed during the process for heating retorts arranged in the wall of the furnace, the heated retorts being used for treatment of materials useful in connection with the production of calcium carbide. For the purpose of rendering carbon monoxide usable for this purpose air was injected into the same before it reached the retorts to be heated, the air being directed so as to exercise suction on the surface of the mixture of lime and carbon. 7 p

I have now observed that if iron oxide is added to the mixture with a suitable change in the proportion of the carbon added the iron oxide may be reduced in the same process, and that furthermore in a process of this character calcium carbonate may be substituted for the lime with substantially the same result as though lime were used. This considerably 5 cheapens the production of calcium carbide smce lime is many times more expensive than the raw product calcium carbonate.

The furnace described in detail in in copending application is. shown in vertical section in the accompanying drawing and may be briefly described for the purpose of the present application, as comprising a side wall section 1 resting in elevated position on a suitable frame 2 and a portable bottom 3 restingon a truck 4, and adapted to be lowered and lifted by means of a threaded element 6. A carbon electrode 7 is transversely supported in the bottom piece 3. which is formed with a central cavity 8, and a second electrode 9 is vertically supported in an adjustable arm 10 to extend the side Wall structure into the cavity 8 in to operative proximity to the first electrode 7. A hopper 11 is provided with a conveyor 12 for feeding the material to be treated into the cavity 8. A radial chamber 13 is formed in the side wall structure 1 and connects with a flue 14 leading to the atmosphere, while a tube 16 extending through the side wall structure into the chamber 13 allows an air-blast to be injected into the gases rising from the cavity 8 for mixing the gases, whereby the latter are rendered combustible and also for reducing suction on the surface of the material to be treated for preventing an equilibrium of pressure from being established.

A retort 17 is supported in the chamber 13 and may be filled with any suitable material it may be desired to treatb subjecting the same to the heat of the pro nets of combustion.

In my present process I use the following materials: calcium carbonate ((12100 carbon (C) and iron oxide (Fe .,O,,) These are 95 mixed and placed in the cavity 8 in suitable proportions and are subjected to the heat of the are, while at the same time suction is produced on the upper surface of the mixture by the tube 16 for carrying off the gases liberated during the process, namely: carbon monoxide and carbon dioxide. The carbon dioxide driven off by the calcining of the calcium carbonate is converted in the presence of carbon into carbon monoxide which functions as a reducing agent for the iron oxide.

The products resulting from these reactions are pig iron, commonly known as cast iron, (LaC or calcium carbide, CO or carbon dioxide, and CO or carbon monoxide, the latter gases being carried ed by the draft and being preferably utilized for heating the retort 17. It should be noted that the above process is not necessarily confined to iron oxide but may be applied to any other oxide that is reducible by heat and carbon.

It should be further understood that lime may be used instead of calcium carbonate, but that it usually is not advisable to use lime since it is much more expensive than calcium carbonate.

It should further be understood that while I preferably use the furnace illustrated in my 20 co-pending. application and shown in part in the present application, anyother electric furnace may be used provided that there should be means for creating a draft which exhausts the furnace-gases as fast as they are evolved by the reduction, prevents the establishment of an equilibrium of pressure and permits of continuous reaction of oxides and HILLIARY ELDRIDGE.

the mixture. 

